Today wireless communication systems are mainly used for human-centered communication and services. A trend is, however, to use wireless communication systems for communication and services mainly involving machines. This kind of communication and services are often referred to as Machine-to-Machine (M2M) communication.
Certain types of communication and services within M2M communication are expected to require that a wireless connection, provided by the wireless communication systems, is highly reliable. The wireless connection is required to be highly reliable both in terms of loss of the wireless connection and the possibility of establishing the wireless connection. In the following, the term “reliable” is used in this context. Therefore, for the above mentioned certain types of communication and services within M2M communication, a high reliability of the connection, or the possibility to establish connection, may be said to be required.
This kind of high reliability may also be required for Person-to-Machine (P2M), Person-to-Person (P2P) and Machine-to-Person (M2P) communication.
Services that may need this kind of high reliability include industrial process control services, services for alarm monitoring, services in smart grid applications, control and management of business and/or mission critical processes or services, services for monitoring critical infrastructure and services towards responders in the national security and public safety segment and other similar services.
Furthermore, high reliability for certain services may be beneficial where deployment of nodes, such as radio base station, radio network controller etc., is particularly costly. At the same time, it is desired to achieve sufficient capacity, e.g. in terms of number of connected devices, and/or coverage for the services.
Consider for example a device, such as smart meters for a smart grid, a metering, sensing or activation device, that is deployed in a network at a remote location at high cost. If there would be a failure in communication with such a device e.g. due to bad coverage and/or insufficient capacity, a manual restoration of the communication with the device or a replacement of the device with another device would be required to compensate for the failure. Such compensation may imply high labor costs, which would scale in an unacceptable manner when there are a great number of devices which often is the case in application of M2M communication.
It is known to provide connectivity for M2M devices in a number of different ways using e.g. wired or wireless connections. The wired connections may be copper wires, optical fibers, Ethernet cables or the like. The wireless connections may be provided by use of various Radio Access Technologies (RATs), such as Wi-Fi, Evolved Universal Terrestrial Radio Access Network for Long Term Evolution (EUTRAN/LTE), Universal Terrestrial Radio Access Network for High Speed Packet Access (UTRAN/HSPA), Global System for Mobile communication (GSM) for Enhanced Data GSM Environment (EDGE) Radio Access Network (GERAN) and the like. Moreover, evolutions of the aforementioned RATs as well as other Third Generation Partnership Project (3GPP) networks may be used to provide the wireless connection.
During planning of the radio access networks and/or telecommunication systems mentioned above, it is sometimes desired to set up the radio access network such as to provide a high reliability for M2M devices. High connectivity could then be provided in the following ways.
For example, the radio access network could be deployed as over-dimensioned in terms of transport and/or radio link resources. Over-dimensioning of transport resources may refer to use of optical fibers for communication from a base station, while a peak bit-rate from the base station is 800 Megabits per second and an optical fiber may handle tens of Gigabits per second. Over-dimensioning of radio link resources refers to deployment of more base stations, antennas, use of more frequency bands, etc. than needed according to an estimated network load. The RAN is said to be over-dimensioned when it is deployed to be able to handle a worst case scenario while still having resources that are available for any upcoming communication.
As another example, so called node availability may be increased by introducing redundancy in a node by installing multiple power units for powering of the node. The node availability may relate to availability of e.g. transport nodes, radio nodes and server nodes, which communicate with the M2M device or control or support the network operation. Node availability decreases on failure of a node, which typically happens when power units for powering of the node breaks down.
As a further example, in some specific network segments, multiple paths could be introduced to avoid single point of failure. An optical fiber ring is able to cope with interruptions of one optical link by routing information in the opposite direction as compared to where the interrupted optical link is located.
During operation of a telecommunication system, it is desired to be able to provide certain quality of service while using the above mentioned radio access network and/or telecommunication system as planned above.
In order to provide certain quality of service, some known radio communication system provides a Quality of Service (QoS) framework. With the QoS framework, a QoS agreement can be set up between a service and the telecommunication system. The QoS agreement for the service typically specifies higher/lower pre-emption priorities, guaranteed vs. best effort data rates, high vs. low transmission delays, high vs. low bit error probability. The bit error probability, or packet error probability, for a specific connection relates to what potential data corruption may occur during a transmission.
In 3GPP EUTRAN/LTE, there is also a concept of Guaranteed Bit-Rate (GBR) and Non-Guaranteed Bit-Rate (NGBR) bearers. The principles for GBR bearers are that e.g. a mobile device requests a GBR bearer from the Radio Access Network (RAN). The GBR is to be used by a service executed in the mobile device. Once the GBR bearer has been established, the RAN will try to maintain the GBR bearer during the ongoing service until the GBR bearer is removed by the service. GBR bearers are typically used for Voice calls for which it is desired to minimize dropping of ongoing calls at the expense of other services or higher probability of blocking a call at setup thereof. A reason for this is that a user of the mobile device is likely more annoyed by a dropped ongoing call than a blocked call at setup.
For the above mentioned business and/or mission critical services, it is likely that an ongoing connection is not required at all, but still a high reliability for connection is required. If a GBR bearer is used for a mission critical service of this kind, resources of the telecommunication system would be consumed at all times, even though no connection is in fact required by the service. A disadvantage with using GBR bearers is hence that is it inefficient in these scenarios.